Electricians, IT personnel, technicians and other individuals who install, route, maintain or otherwise work with wire cabling, such as armored cables (AC), non-metallic (NM-B) cables, underground feeder (UF) cables, coaxial cables, Ethernet (Cat-5e) cables, among other well-known commercially available cables and wires often encounter difficulties in identifying which cable among a plurality of cables is routed to a particular source and/or load of interest, or may be suspected of failing to deliver a required current flow to its load because of being physically damaged. Various test devices are known in the art to assist a technician in the field to identify or otherwise distinguish a particular electrical cable from other electrical cables in the vicinity.
U.S. Pat. No. 4,736,158 discloses a device for identifying wires extending between two spaced-apart test units, i.e., a source unit and a destination unit. The wire identification is achieved by implementing different resistive loads at the destination unit and selectively sending a current from the source unit to the destination unit. Logic circuitry is provided to identify which wire is carrying the current from the source unit to the destination unit.
U.S. Pat. No. 5,055,793 discloses a transmitter having an LC tank circuit and a loop antenna for transmitting an inductively created alternating current (AC) signal at a predetermined operating frequency along an underground cable, which in turn generates an alternating electromagnetic field in response to the current flow. A portable receiver unit can detect the electromagnetic field produced by the alternating current along the cable.
U.S. Pat. No. 5,929,624 discloses a method of detecting the presence of an armored cable by injecting a pulsed current onto the armored shielding which is grounded, and using a detector to detect the pulsed signal at a remote location. Alternatively, U.S. Pat. No. 7,902,810 discloses a device for injecting current over a cable and detection of an AC signal that is derived by capacitive coupling of the input signal produced on the cable.
The prior art current injection and detection devices include various complex logic circuitry and/or the use of specialized signal detection devices for injecting and detecting current in a conductive cable. These test devices can be expensive to manufacture and cumbersome to operate. Accordingly, it would be desirable to provide a simple to use, low cost, portable electrical testing device that can inject an alternating current on a cable to assist a technician with identifying a particular cable in a cable bundle, or a ground fault location in a cable, or conduct other electrical tests which require an injected current. It is further desired to be able to detect an injected signal over a conductive wire or cable with a conventional, commercially available amp/voltage meter.